Double-edge triggered scannable pulsed flip-flop for high frequency and/or low power applications

Abstract

A circuit for data storage is presented. The circuit includes clock generation circuits for generating a pulse clock signal having first and second clock pulses for each clock cycle of a system clock and first and second scan clock signals. The circuit further includes a scannable pulse flip-flop circuit having a data input and a data output that are connected with an internal storage node, and a scan input and a scan output that are also connected with the internal storage node. In a function mode of operation, the first and second scan clock signals are held at a logic level to allow data to pass from the data input to the internal storage node at the first clock pulse and from the internal storage node to the data output at the second clock pulse signal. In a scan mode of operation the pulse clock signal is held at a logic level to allow data to pass from the scan input to the internal storage node at a pulse of the first scan clock signal and from the internal storage node to the scan output at a pulse of the second scan clock signal.

1 . A circuit for data storage, comprising:
 a double edge clock generation circuit for generating a pulse clock signal having first and second clock pulses for each clock cycle of a system clock;   a scan clock generation circuit for generating first and second scan clock signals; and   a scannable pulse flip-flop circuit having a data input and a data output that are connected with an internal storage node, the scannable pulse flip-flop circuit further having a scan input and a scan output that are connected with the internal storage node, the scannable pulse flip-flop circuit receptive to the pulse clock signal and the scan clock signals, the scannable pulse flip-flop circuit is configured to be operable in a function mode of operation and a scan mode of operation, in the function mode of operation the first and second scan clock signals are held at a logic level to allow data to pass from the data input to the internal storage node at the first clock pulse and from the internal storage node to the data output at the second clock pulse signal, in the scan mode of operation the pulse clock signal is held at a logic level to allow data to pass from the scan input to the internal storage node at a pulse of the first scan clock signal and from the internal storage node to the scan output at a pulse of the second scan clock signal.   
   
   
       2 . The circuit of  claim 1  wherein the scannable pulse flip-flop circuit further comprises an inverter at the data output for inverting the data at the data output. 
   
   
       3 . The circuit of  claim 1  wherein the scannable pulse flip-flop circuit further comprises an inverter at the scan output for inverting the data at the scan output. 
   
   
       4 . The circuit of  claim 1  wherein the double edge clock generation circuit comprises:
 a clock pulse generation circuit for generating the first clock pulse at a rising edge of each clock cycle of a system clock and the second clock pulse at the falling edge of each clock cycle of a system clock; and   an AOI circuit is connected to the scan output of the scannable pulse flip-flop circuit, in the scan mode of operation the pulse clock signal is held at the logic level by the AOI circuit in response to data at the scan output.   
   
   
       5 . The circuit of  claim 4  wherein the double edge clock generation circuit further comprises:
 an inverting clock delay circuit for introducing a delay to the system clock.   
   
   
       6 . The circuit of  claim 4  further comprising:
 a negative edge-triggered flip-flop connected to the AOI circuit for holding the pulse clock signal at the logic level.   
   
   
       7 . The circuit of  claim 1  wherein the scan clock generation circuit further generates the first and second scan clock signals such that they are underlapping. 
   
   
       8 . The circuit of  claim 1  further comprising a plurality of the scannable pulse flip-flop circuits configured as registers, wherein one of the scannable pulse flip-flop circuits comprises one of the registers for storage of a single bit, the registers further configured in register rows, wherein the number of registers in a row corresponds to a number of bits in a word. 
   
   
       9 . A method of data storage, comprising:
 generating a pulse clock signal having first and second clock pulses for each clock cycle of a system clock;   generating first and second scan clock signals;   in a function mode, holding the first and second scan clock signals are held at a logic level, passing data from the data input to the internal storage node at the first clock pulse, and   passing data from the internal storage node to the data output at the second clock pulse signal; and   in the scan mode, holding the pulse clock signal at a logic level, passing data from the scan input to the internal storage node at a pulse of the first scan clock signal, and passing data from the internal storage node to the scan output at a pulse of the second scan clock signal.   
   
   
       10 . The method of  claim 9  further comprising inverting the data at the data output. 
   
   
       11 . The method of  claim 9  wherein further comprising inverting the data at the scan output. 
   
   
       12 . The method of  claim 9  wherein the generating the pulse clock signal comprises:
 generating the first clock pulse at a rising edge of each clock cycle of a system clock and the second clock pulse at the falling edge of each clock cycle of a system clock; and   in the scan mode of operation, holding the pulse clock signal at the logic level in response to data at the scan output.   
   
   
       13 . The method of  claim 12  wherein the generating the pulse clock signal comprises:
 delaying the system clock.   
   
   
       14 . The method of  claim 9  wherein the generating the first and second scan clock signals further comprises underlappingly generates the first and second scan clock signals. 
   
   
       15 . The method of  claim 9  further comprising the steps of the function and scan modes are repeated for multiple bits.